The phylum Porifera includes sponges. These are primitive multi-celled animals that attach themselves to the sea floor. They filter the seawater to extract food particles. Some fossil sponges show the exit opening for filtered water.

Example of a sponge from the Cap Blanc Nez cenomaan

Most sponges have a skeleton made of tiny skeletal elements(spicules or sponge needles) which consists of horn, lime or silica. The presence of these needles of fossil spongesis visible under magnification. The subdivision of the sponges is based on the type of skeleton. Keratin Sponges(Demospongiae), Lime Sponges(Calcispongiae) or Silica or Glass Sponges(Hexactinellida). Sponges with a silica skeleton fossilize quite easily. Especially indeposits from the Cretaceousperiod, fossil sponges are common. The oldest known sponges are from the Precambrian period.

Example of a sponge from Paulmy, France.

Photos or locations of Porifera at this site

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